Concrete is used in many different types of construction projects, including, but not limited to walls, retaining walls, bridges, roadways, building foundations, etc. . . . . Concrete is a composite material that is composed of coarse aggregate bonded together with a fluid cement that hardens over time. Concrete may be poured off-site in forms to obtain a concrete structure in a desired shape and then transported on-site to be installed or it may be poured on-site in field constructed forms.
It is known that most applications require one to reinforce concrete components using reinforcing members. In most cases, the reinforcing members are composed of corrosion susceptible steel, such as reinforcing bar or rebar. However, over time steel will degrade into iron oxide commonly referred to as rust. This degradation will eventually diminish the integrity of the rebar, and thus, the concrete structure. In many applications steel rebar may have a deformity, i.e., a deformed pattern that is designed to increase the friction between rebar and the material in which it is embedded.
Recent attempts to overcome the shortcomings of steel rebar utilize reinforcing bars composed of carbon fibers. In general, carbon fiber based rebar is comprised of a plurality of unidirectional glass fibers that have been reinforced or thermoset with resin. The widely accepted properties of carbon fiber strands indicate that a member with a small cross-section will perform quite well in tension, but very poorly in shear. This is a fact that was experimentally confirmed during testing of a carbon fiber rebar (CF) with parallel carbon fiber strands. It was also found that a CF sample wherein all fibers are parallel with no surface deformations does not have sufficient bond strength with a cementitious material. This fact has since been confirmed by the American Concrete Institute (ACI) (440.6-3). The ACI goes as far as to require suppliers of fiber reinforced polymer (FRP) to provide the method by which the surface of the FRP is deformed.
The deformed pattern may be replicated by “pinching” of the fibers prior to being set by the resin. However, this does not overcome the deficiencies of carbon fiber based rebar over steel rebar.
It may be further desireable to be able to attach or couple components, e.g., building components to a pre-stressed, pre-cast concrete structure. However, it is rather difficult to attach such components directly to the concrete structure. Past attempts have involved embedded a substrate into the concrete structure to which the components could then be fastened. However, during production of the concrete structure, the concrete structure will contract once the tension on the reinforcing members is released. If the embedded substrate does not contract at the same rate, then the substrate may warp and/or the concrete structure may be weakened.
The present invention is aimed at one or more of the problems set forth above.